Pneumatic impact tool

ABSTRACT

The invention relates to lightweight scaling tools for scaling loose hanging rocks in mine areas and the like. The device includes a cylindrical wall forming a piston chamber and a piston reciprocally mounted therein. The piston is reciprocated by fluid under pressure, suitable passages being provided in the piston itself which cooperate with radial ports in the cylindrical wall. The piston actuates a reciprocally mounted striker bar which engages the loose rocks.

United States Patent Inventor Joseph Marcenuk 7492 Wiltshire Drive, North Surrey, British Columbia, Canada Appl. No. 809,849 Filed Mar. 24, 1969 Patented Mar. 30, 1971 PNEUMATIC IMPACT TOOL 9 Claims, 6 Drawing Figs.

U.S.Cl 173/115, 173/134, 173/169, 299/69 Int. Cl. B25d 7/00, B25d 9/04, B25d 17/04 Field olSearch 173/115, 134, 169; 92/154; 299/69, 70

Primary Examiner-Ernest R. Purser Att0rneyWeir, Marshall, Mac Rae & Lamb ABSTRACT: The invention relates to lightweight scaling tools for sealing loose hanging rocks in mine areas and the like. The device includes a cylindrical wall forming a piston chamber and a piston reciprocally mounted therein. The piston is reciprocated by fluid under pressure, suitable passages being provided in the piston itself which cooperate with radial ports in the cylindrical wall. The piston actuates a reciprocally mounted striker bar which engages the loose rocks.

Patented March 30, 1971 2 Sheets-Sheet 1 ..1'n11/11I/II/ll/lIllfIl/l/l/lI/Ill/lIIIIIIIIIIIIIlI/II!III/IIr!III/lllllllllI/lrlll/I!Il/Ill/l/lr/llfll/IIl/l PATENT AGENT Patented March 30, 1971 2 Sheets-Sheet 2 6 144 fin Z PATENT AGENT 1 Ncumafi ALDEHIA \NU /nv 8112 NEON-PAH PNEUMATIC KMPACT TOOL Prior art devices of the pneumatic drill type are not usually used for scaling purposes because their weight and bulk makes them too cumbersome for this type of use. Moreover, such devices are of restricted length which minimizes their efficiency and makes them dangerous to operate for sealing work.

Thus, scaling tools most commonly used in mines today are of the manual impact type. Such a tool is usually a one-piece hollow rod with a steel tip. Since it is eight to fourteen feet in length and one and a half to two inches in diameter, it is difficult to manipulate in many areas where space is limited and it is frequently impossible to apply sufficient impact force for the purpose.

The present invention seeks to provide a scaling tool of the pneumatic type which is of sufficiently lightweight and compact form that it can be operated by one man in areas of restricted volume with convenience, safety, and effectiveness.

The invention also seeks to provide a scaling tool of the character described that is of simple structure and manufacture, and readily adjustable as to operative length.

The invention will be described with reference to the accompanying drawings, in which FIG. 1 is a side elevation of the portable scaler, partly in section, in accordance with the invention,

FIG. 2 is a section of the portable scaler taken on line 2-2 of FIG. 1,

P16. 3 is an isometric view of an alternative design of the end insert member,

FIG. 4 is a side view, partly in section, of still another form of the end insert member,

FIG. 5 is a view, partly .in section, of the quick release mechanism in accordance with the invention, and

FIG. 6 is a comparison diagram of the oscillating stroke of the piston in accordance with the invention.

in the drawings, the scaler generally is designated by the numeral 10. As shown, it comprises an assembly of component parts for convenience in manufacture and ease of replacement of broken or worn out parts. Primarily, the essential components, as shown in FIG. 1, comprise a casing 11, a piston 12, and a striker rod assembly 14.

Casing 11 is of elongated tubular or hollow cylindrical form and is preferably composed of a plurality of individual lengths 17, 18, 19 connected to each other by couplings 20, 21 which, in the device illustrated, also constitute transverse dividing walls providing separate chambers 22, 23, 24 within the casing. The casing has a forward end provided with a nose cap 25 and a rearward end closed by closure cap 26.

Piston 12 is reciprocatably mounted in chamber 23 and comprises a right cylindrical portion 27 in sliding engagement with the interior wall surface of the casing and an axial cylindrical portion 28 of reduced diameter projecting forwardly through an axial opening 29 in coupling into chamber 22.

Piston portion 27 has an axial extend considerably less than the axial extent of chamber 23 to permit forward and rearward reciprocating strokes of the piston therein. The annular forward face 30 is, of course, of considerably less area than that of the full rearward face 31.

Piston portion 27 has therein a forward circumferential groove 32, a plurality of passages 33 leading from groove 32 to rearward face 31, a rearward circumferential groove 34, and a plurality of passages 34a leading from groove 34 to forward face 30.

Casing chamber 23 has a forward port 35 open to atmosphere which is placed in and out of communication with the space 23a in chamber 23 forwardly of face 30 during reciprocation of the piston and a rearward port 36 open to atmosphere which is placed in and out of communication with the space 23b in chamber 23 rearwardly of face 31 during reciprocation of the piston.

Casing chamber 23 also has a pressure fluid inlet port 37 intermediate ports 35 and 36. In one position of piston 12, port 37 is closed by a portion 38 of the piston wall between grooves 32 and 34. As the piston moves forwardly of such position,

groove 34 is placed in communication with port 37 and as the piston moves rearwardly of such position, groove 32 is placed in communication with port 37.

The striker rod assembly 14 comprises a rod 39, which may be of hollow steel tubing, reciprocatably mounted in casing section 17 with its rear end portion supported in a bearing collar 40 and its forward end portion supported in a bearing collar 41. The rear end portion of rod 39 extends into chamber 22 and has a flat-faced striker plug 42.

it will be apparent that striker plug 42 is adapted to receive a succession of force-imparting blows from piston 12 during reciprocation thereof by engagement with plug 42 of the confronting end face of piston portion 28. Plug 42 is preferably of hardened steel or other metal to withstand such blows.

Rod 39 extends through nose cap 25 and an extension rod 43 is detachably fixed to its end by means of a coupling 44. It will be apparent that the effective length of striker rod 39 may be increased or decreased as desired by adding or removing extension rods 43 with appropriate couplings.

A bit or tool insert45 is detachably mounted on the end of the striker rod assembly as, for instance, by inserting a recessed end portion of tool 45 into the open end of a rod 43 and driving taper pins 46 through aligned apertures in the rod and tool end portion.

Means for adjustably limiting the free travel reciprocating movement of the striker rod is preferably provided and, as shown, comprises a circumferential rib or shoulder 47 fixedon rod 39 in casing section 18 adjacent nose cap 25. A bush 48, preferably of resilient material such as rubber, is seated against nose cap 25 for striking engagement by shoulder 47 on forward movement of the rod 39. Rearward movement of the rod is limited by engagement with collar 41.

Length of stroke of the rod 39 may be adjusted by screwthreaded mounting of the nose cap 25 in casing section 18 with axial threaded movement of the nose cap (and bush 48) to desired position and locking of the cap in such position by means of setscrew 48a. Alternate a. additional adjustment may be effected by screw threaded mounting of the collar 41 in the nose cap thus making possible axial movement of collar 41 to a desired position and locking of the collar in such position by a setscrew 49.

Means for supplying fluid under pressure such as compressed air to port 37 comprises, as shown a D-shaped hollow handle 50 having a main gripping portion 51 and a pair of legs 52, 53 fixed to the casing. The interior of leg 52 communicates with port 37 and the interior of portion 51 through a port 54. The interior of leg 53 communicates with the interior of portion 51 through a port 55 and with chamber 24 through a port 56. Chamber 24 is supplied with fluid under pressure such as compressed air from a suitable source via conduit 57 which communicates with chamber 24 through end cap 26.

Flow of compressed air through the handle to port 37 is controlled by valve means which, as shown, comprises a barrel 58 in handle portion 51 having a port 59 in registry with port 54. Barrel 58 communicates with interior of handle portion 51 through an end port 60 which is closed and opened by a poppet valve 61. Valve 61 is normally held in closed position by means of a spring 62 on valve stem 63 and located between the closed end 64 of the barrel and a shoulder 65 in the barrel.

Valve stem 63 projects through end 64 and is in engagement with an arm of a bellcrank lever 66 pivotally mounted on the handle at 67 and having a pin and slot connection 68 with a trigger 69 pivotally mounted on the handle at 70. it will be apparent that the trigger 69 may be manually actuated as desired to close or open port 60 and thus supply or interrupt the supply of compressed air to port 37 Automatic lubricating means for the piston and piston chamber is preferably provided. As shown, such means comprises a transverse partition member 71 in chamber 24 separating a portion 24a thereof from the compressed air inlet portion thereof. Chamber portion 24a contains a packing and is supplied with oil through an inlet 72 provided with a plug 73. Partition 71 has a plurality of apertures 74 therein. Thus,

during flow of compressed air through chamber 24 a limited supply of oil will be sucked into the air stream from chamber 24a through apertures 74 and fed to the piston chamber 23.

Preferably, the device is provided with a carrying strap 75 for the ease of transport and operation. Strap 75 is connected to a bank 76 on the rearward end of the casing and to a band 77 on the forward end of the casing. The front band 77 may include quick release means 78 which may be useful in emergency situations. As shown in FIG. 5, the quick release means may comprise a pair of parallel spaced lugs 79 on band 77 having aligned apertures 80 therein, and a pin 81 adapted to be inserted through apertures 80 and to frictionally engage the walls thereof. Strap 75 has an aperture 82 adjacent its end for reception of the pin when the end portion of the strap is placed between lugs 79 and aperture 82 aligned with apertures 80. The pin is carried by a cord 83 connected to the casing.

In operation, assuming the piston 12 is moving towards the rear and port 37 (undersupply of compressed air) is being placed in communication with groove 32, air will flow from port 37 through groove 32, passages 33, into space 23a (port 36 being closed) thus forming a cushion therein which will slow the piston down to a stop to complete its rearward stroke. Air pressure in space 234 will, of course, continue to build up and will propel the piston forwardly to perform its forward stroke, space 23b having been exhausted to atmosphere via port 35.

Air will still be admitted to chamber space 23a until the piston reaches its center of stroke when port 37 is closed by piston portion 38 at which time the piston will have reached its approximate maximum velocity of forward stroke. Immediately thereafter, space 23a is exhausted to atmosphere via port 36 and groove 34 is placed in communication with port 37 and air pressure builds up in chamber space 23b via passages 340. This air pressure will provide a cushioning effect which will finally bring the piston to a stop at the end of its forward stroke in spaced adjacent relation to wall 20.

The end face of piston portion 28 will in the meantime have delivered a hammer blow to the end of striker rod 39 which will be in its rearward position with its stroke suitably adjusted by adjusting movement of the collar 41 and/or nose cap 25.

Referring to FIG. 6, if the piston were allowed to reciprocate freely under air pressure without contact with a striker rod, the profile would be substantially as shown in the extended full line. Under operative conditions such as described, the piston under air pressure would flow a velocity profile substantially as shown in dotted lines. The point X has been indicated as about the most desirable point for the piston to deliver an impact blow to the striker bar to take advantage of maximum power.

It will be apparent that, since the face 31 of the piston is of considerably less area than that of face 30, the forward thrust of the piston will be made at greater velocity and power than the return stroke.

It has been found that air pressures of from 50 p.s.i. to 60 p.s.i. are sufficient for effective operation of the device. However, higher pressures may be employed in certain mine areas where dislodgment of loose rocks is difficult with lower pressures.

It is contemplated that several parts of the device as described, including the casing and handle, will be formed of lightweight metal such as aluminum or aluminum alloys. A fully effective device of an overall weight-of about 13 pounds has been constructed in accordance with the invention.

It will be apparent that any desired type of tool insert may be employed. That indicated at 45 in FIGS. 1 and 3 is of simple chisel type. Another type 84 is shown in FIG. 4 and comprises a shank 85 for detachable reception in the end of rod 43 and a cup-shaped magnetic head 86 for reception of a mating end portion 87 of a spike or like tool 88.

It will be understood that, for unrestricted air flow, the total cross-sectional area of groove 32 and passages 33, as well as the total cross-sectional area of groove 34 and passage 34a, is at least as great as that of port 37. Furthermore, the cross-sectional area of each of the exhaust ports 35 and 36 is at least as great as that of port 37.

I claim:

1. A portable scaling tool comprising a cylindrical wall forming a hollow casing having a forward end, a rearward end, a closure cap at each said end, and spaced transverse walls forming with a portion of said cylindrical wall a piston chamber therebetween, a striker rod axially and reciprocally mounted in said casing and having an impact end within said casing and an end tool-receiving portion extending outwardly of said casing through said forward cap, a piston reciprocally mounted in said chamber and having a rearward portion of maximum diameter in sliding engagement with said cylindrical wall and a forward portion of reduced diameter extending through and in sliding engagement with one of said transverse walls, said reduced diameter portion having an impact face in confronting relation to said impact end of said striker rod for successive engagement therewith, said chamber-forming portion of said cylindrical wall having forward and rearward ports open to atmosphere and an intermediate fluid inlet port having a connection to a source of fluid under pressure, said piston having a forward annular groove, a rearward annular groove, a full diameter section between said grooves, a rear substantially full diameter face, a front annular face extending around said reduced diameter portion, a plurality of passages leading from said forward groove to said rear face, and a plurality of passages leading from said rearward groove to said front face, said piston having a first position in which said forward groove is in communication with said fluid inlet port and a forward portion of said chamber is open to atmosphere through said forward port and a second position in which said rearward groove is in communication with said fluid inlet port and a rearward portion of said chamber is open to atmosphere through said rearward port, and means for adjusting the stroke of said striker rod which comprises a pair of spaced bushes through which said rod extends within said casing, an annular shoulder fixed to said rod and located between said bushes, and means for adjusting the axial position of a first one of said bushes relatively to said casing.

2. A portable scaling tool as defined in claim 1, said pressure fluid connection comprising a handle fixed to said casing and having a fluid passage therein, said casing having a second chamber therein, conduit means for supplying fluid under pressure to said second chamber, said handle passage having a branch leading to said second chamber and a branch leading to said fluid inlet port, valve means in said handle passage, and manually operable means for controlling said valve means.

3. A portable scaling tool as defined in claim 2, including piston lubricating means comprising a transverse wall having apertures therein defining in part said second chamber and defining in part a third chamber, and an oil-retaining packing in said third chamber.

4. A portable scaling tool as defined in claim 1, the second one of said bushes being of elastically resilient material.

5. A portable scaling tool as defined in claim 1, said first bush constituting a bearing support for said rod.

6. A portable scaling tool as defined in claim 4, said second bush being positioned in said forward end cap, said forward end cap having a screw-threaded mounting in said casing for axial adjustment with respect thereto, said first bush having a screw-threaded mounting in said forward end cap for axial adjustment with respect thereto, and means for locking each of said forward end cap and said first bush in adjusted position.

7. A portable scaling tool as defined in claim 1, said casing comprising a plurality of interconnected longitudinal sections.

8. A portable scaling tool as defined in claim 7, each said transverse wall having threaded connection with a pair of said sections to constitute coupling means therefor.

9. A portable scaling tool as defined in claim 1, said striker rod having a detachable section externally of said casing, said detachable section having a tool insert removably mounted on the end thereof. 

1. A portable scaling tool comprising a cylindrical wall forming a hollow casing having a forward end, a rearward end, a closure cap at each said end, and spaced transverse walls forming with a portion of said cylindrical wall a piston chamber therebetween, a striker rod axially and reciprocally mounted in said casing and having an impact end within said casing and an end tool-receiving portion extending outwardly of said casing through said forward cap, a piston reciprocally mounted in said chamber and having a rearward portion of maximum diameter in sliding engagement with said cylindrical wall and a forward portion of reduced diameter extending through and in sliding engagement with one of said transverse walls, said reduced diameter portion having an impact face in confronting relation to said impact end of said striker rod for successive engagement therewith, said chamber-forming portion of said cylindrical wall having forward and rearward ports open to atmosphere and an intermediate fluid inlet port having a connection to a source of fluid under pressure, said piston having a forward annular groove, a rearward annular groove, a full diameter section between said grooves, a rear substantially full diameter face, a front annular face extending around said reduced diameter portion, a plurality of passages leading from said forward groove to said rear face, and a plurality of passages leading from said rearward groove to said front face, said piston having a first position in which said forward groove is in communication with said fluid inlet port and a forward portion of said chamber is open to atmosphere through said forward port and a second position in which said rearward groove is in communication with said fluid inlet port and a rearward portion of said chamber is open to atmosphere through said rearward port, and means for adjusting the stroke of said striker rod which comprises a pair of spaced bushes through which said rod extends within said casing, an annular shoulder fixed to said rod and located between said bushes, and means for adjusting the axial position of a first one of said bushes relatively to said casing.
 2. A portable scaling tool as defined in claim 1, said pressure fluid connection comprising a handle fixed to said casing and having a fluid passage therein, said casing having a second chamber therein, conduit means for supplying fluid under pressure to said second chamber, said handle passage having a branch leading to said second chamber and a branch leading to said fluid inlet port, valve means in said handle passage, and manually operable means for controlling said valve means.
 3. A portable scaling tool as defined in claim 2, including piston lubricating means comprising a transverse wall having apertures therein defining in part said second chamber and defining in part a third chamber, and an oil-retaining packing in said third chamber.
 4. A portable scaling tool as defined in claim 1, the second one of said bushes being of elastically resilient material.
 5. A portable scaling tool as defined in claim 1, said first bush constituting a bearing support for said rod.
 6. A portable scaling tool as defined in claim 4, said second bush being positioned in said forward end cap, said forward end cap having a screw-threaded mounting in said casing for axial adjustment with respect thereto, said first bush having a screw-threaded mounting in said forward end cap for axial adjustment with respect thereto, and means for locking each of said forward end cap and said first bush in adjusted position.
 7. A portable scaling tool as defined in claim 1, said casing comprising a plurality of interconnected longitudinal sections.
 8. A portable scaling tool as defined in claim 7, each said transverse wall having threaded connection with a pair of said sections to constitute coupling means therefor.
 9. A portable scaling tool as defined in claim 1, said striker rod having a detachable section externally of said casing, said detachable section having a tool insert removably mounted on the end thereof. 